My Cavalier is throwing P0440

[Steve]

I know it's not a truck, but my 1999 Cavalier is throwing a P0440 code - EVAP small leak, no flow condition.

Four probably causes.

1) Defective fuel cap
2) EVAP canister or host cracked
3) Purge of vent solenoid defective
4) Vacuum leak at engine.

Anyone have experience with this code? I guess I'll just start at the top and work down.

[84fiero123]

Start with 4,
Then 2, they are kind of related,
Then 1,
And lastly 3
Start with the ones that cost no money to check.

[Steve]

That's basically my plan.

[Steve]

I think I posted this in another thread. I cleaned up the gas cap and the filler cap insert and got rid of some grime, I let the system run a couple of cycles and the code reset itself and hasn't come back.

[Gmcsuvguy]

I've seen them leak at the fuel sender unit o-ring on the tank. Try the little (easy) fixes first, or take it into a shop that has a smoke machine, they hook up the smoke machine and pump smoke through the evap system and look where the smoke is coming out from.